That is a fair point - however if it isn't worth it, then why are companies overseas doing it?
I think most of them are building their infrastructure right now or wealthy enough they pay for it.
If a country with very little internet, today, was going to build infrastructure, they would obviously use the best technology. I can't imagine the cost of laying fiber cable is that much higher than laying coaxial cable. So, they take the initial hit on materials up front. In the US, we already have infrastructure built and the costs of replacing it aren't as lucrative.
Singapore is a great example. 1 in 6 people can easily afford high speed internet. Can 1 in 6 Americans afford $100 a month for what is an entertainment luxury? So, Singapore has a huge market waiting to be tapped, America already has a market basically saturated. New development isn't going to add a lot of new customers, just switch from the legacy system to the new one. That isn't (without a large increase in price) going to be worth it for most businesses.
Now, the geographical monopoly doesn't help consumers either. As, there won't be many new services, using the new technologies coming in to compete.
And, we have to come to a point where internet is "good enough" for the majority of people. And it is quickly getting there in the US. The average person won't saturate their 50mb connection, let alone a 1000mb. Sure, it would be nice for people that could use it (most of this forum, I'd assume), but that is a very small market.